Scheme 1.

Synthesis of [2]PF₆, [3]PF₆, [4]PF₆, and [5]PF₆ from [1 a]PF₆ and the structures of the four possible coordination isomers obtained. Note that, in order to obtain isomers c and d, the polypyridyl ligands must rearrange so the σ‐bound C atom becomes trans to the entering N,S ligand. For clarity, only the Λ isomers are shown, but all samples were obtained as racemic Δ/Λ mixtures.